Dhaval, > What version of HBase are you running? 0.94.7
> How many region server handlers do you have? 100 We are following this issue: https://issues.apache.org/jira/browse/HBASE-9087 Ted, we think too that splitting may incur in a better performance. But like you said, it must be done manually. Thanks! On Wed, Jul 31, 2013 at 2:14 PM, Dhaval Shah <[email protected]>wrote: > Looking at https://issues.apache.org/jira/browse/HBASE-6136 it seems like > the 500 Gets are executed sequentially on the region server. > > Also 3k requests per minute = 50 requests per second. Assuming your > requests take 1 sec (which seems really long but who knows) then you need > atleast 50 threads/region server handlers to handle these. Defaults for > that number on some older versions of hbase is 10 which means you are > running out of threads. Which brings up the following questions - > What version of HBase are you running? > How many region server handlers do you have? > > Regards, > Dhaval > > > ----- Original Message ----- > From: Demian Berjman <[email protected]> > To: [email protected] > Cc: > Sent: Wednesday, 31 July 2013 11:12 AM > Subject: Re: help on key design > > Thanks for the responses! > > > why don't you use a scan > I'll try that and compare it. > > > How much memory do you have for your region servers? Have you enabled > > block caching? Is your CPU spiking on your region servers? > Block caching is enabled. Cpu and memory dont seem to be a problem. > > We think we are saturating a region because the quantity of keys requested. > In that case my question will be if asking 500+ keys per request is a > normal scenario? > > Cheers, > > > On Wed, Jul 31, 2013 at 11:24 AM, Pablo Medina <[email protected] > >wrote: > > > The scan can be an option if the cost of scanning undesired cells and > > discarding them trough filters is better than accessing those keys > > individually. I would say that as the number of 'undesired' cells > decreases > > the scan overall performance/efficiency gets increased. It all depends on > > how the keys are designed to be grouped together. > > > > 2013/7/30 Ted Yu <[email protected]> > > > > > Please also go over http://hbase.apache.org/book.html#perf.reading > > > > > > Cheers > > > > > > On Tue, Jul 30, 2013 at 3:40 PM, Dhaval Shah < > > [email protected] > > > >wrote: > > > > > > > If all your keys are grouped together, why don't you use a scan with > > > > start/end key specified? A sequential scan can theoretically be > faster > > > than > > > > MultiGet lookups (assuming your grouping is tight, you can also use > > > filters > > > > with the scan to give better performance) > > > > > > > > How much memory do you have for your region servers? Have you enabled > > > > block caching? Is your CPU spiking on your region servers? > > > > > > > > If you are saturating the resources on your *hot* region server then > > yes > > > > having more region servers will help. If no, then something else is > the > > > > bottleneck and you probably need to dig further > > > > > > > > > > > > > > > > > > > > Regards, > > > > Dhaval > > > > > > > > > > > > ________________________________ > > > > From: Demian Berjman <[email protected]> > > > > To: [email protected] > > > > Sent: Tuesday, 30 July 2013 4:37 PM > > > > Subject: help on key design > > > > > > > > > > > > Hi, > > > > > > > > I would like to explain our use case of HBase, the row key design and > > the > > > > problems we are having so anyone can give us a help: > > > > > > > > The first thing we noticed is that our data set is too small compared > > to > > > > other cases we read in the list and forums. We have a table > containing > > 20 > > > > million keys splitted automatically by HBase in 4 regions and > balanced > > > in 3 > > > > region servers. We have designed our key to keep together the set of > > keys > > > > requested by our app. That is, when we request a set of keys we > expect > > > them > > > > to be grouped together to improve data locality and block cache > > > efficiency. > > > > > > > > The second thing we noticed, compared to other cases, is that we > > > retrieve a > > > > bunch keys per request (500 aprox). Thus, during our peaks (3k > requests > > > per > > > > minute), we have a lot of requests going to a particular region > servers > > > and > > > > asking a lot of keys. That results in poor response times (in the > order > > > of > > > > seconds). Currently we are using multi gets. > > > > > > > > We think an improvement would be to spread the keys (introducing a > > > > randomized component on it) in more region servers, so each rs will > > have > > > to > > > > handle less keys and probably less requests. Doing that way the multi > > > gets > > > > will be spread over the region servers. > > > > > > > > Our questions: > > > > > > > > 1. Is it correct this design of asking so many keys on each request? > > (if > > > > you need high performance) > > > > 2. What about splitting in more region servers? It's a good idea? How > > we > > > > could accomplish this? We thought in apply some hashing... > > > > > > > > Thanks in advance! > > > > > > > > > > >
